It is known to produce laminated components for electrical machines by pressing stacks of annular laminations together. The laminations are typically formed from sheets of electrical grade steel which are usually provided with insulating coatings. Each annular lamination may be formed of a single member or may itself be of segmental construction with the segments abutted against each other e.g. at generally radially extending edges.
In a normal arrangement the laminations are provided in axial sections with a plurality of stacked laminations in each section. Between each section, passageways or ducts may be provided for cooling fluid, e.g. air, which extend generally radially. More particularly, in an electrical machine having a rotor and a stator the radial inner or outer ends of the passageways will communicate with the air gap between the rotor and stator.
It is known to form these passageways by utilising spacers such as beams or cylindrical members, the latter type commonly being referred to as pins. Such spacers are affixed mechanically or by welding, e.g. spot welding, to the face of an end lamination of one section. The spacers then abut the face of the adjacent end lamination of the neighbouring section to define a passageway therebetween. The production and attachment of such spacers is a complex and expensive undertaking, even where a single common mass produced part such as pins is used. A passageway that is defined by a plurality of pins arranged in a predetermined pattern offers certain advantages in terms of cooling efficiency but still requires large air flow rates to cool the laminated component.